Damping mechanisms and order-to-chaos transition in the warm rotating {sup 163}Er nucleus

Journal Article · Thu Sep 01 00:00:00 EDT 2005 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PhysRevC.72.034307· OSTI ID:20698976

Leoni, S; Benzoni, G; Bracco, A; Blasi, N; Camera, F; Grassi, C; Mason, P; Million, B; Paleni, A; Pignanelli, M; Vigezzi, E; Wieland, O ^[1]; Matsuo, M ^[2]; Doessing, T; Herskind, B; Hagemann, G B; Wilson, J ^[3]; Maj, A; Kmiecik, M ^[4]; Lo Bianco, G ^[5]

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1. Dipartimento di Fisica, Universita di Milano and INFN Sez. Milano, Via Celoria 16, I-20133 Milan (Italy)
2. Graduate School of Science and Technology, Niigata University, Niigata 950-2181 (Japan)
3. Niels Bohr Institute, Blegdamsvej 15-17, DK-2100 Copenhagen (Denmark)
4. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, PL-31-342 Cracow (Poland)
5. Dipartimento di Fisica, Universita di Camerino and INFN Sez. Perugia (Italy); and others

The {gamma} decay in the quasicontinuum is used to study the order-to-chaos transition in the thermally excited {sup 163}Er nucleus. The experimental analysis is performed on high-statistics EUROBALL data, focusing on the spin region I{approx_equal}(20-40)({Dirac_h}/2{pi}), and internal excitation energy up of {approx_equal}2.5 MeV. The results are compared to cranked shell model calculations for this nucleus, taking into account the dependence on the K quantum number. Two main topics are investigated. First, the validity of the selection rules associated with the K quantum number are studied as a function of the internal energy U above yrast. K-selection rules are found to be obeyed in the decay along discrete unresolved rotational bands up to U{approx_equal}1.2 MeV, whereas in the interval U{approx_equal}1.2-2.5 MeV, where the order-to-chaos transition is expected to take place, selection rules are found to be only partially valid. Second, the line-shape analysis of {gamma}-{gamma} coincidence spectra provides a direct experimental measurement of the rotational and compound damping widths ({gamma}{sub rot} and {gamma}{sub {mu}}), yielding values of 200 and 20 keV, respectively, in good agreement with theory.

• OSTI ID: 20698976
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 72, Issue 3; Other Information: DOI: 10.1103/PhysRevC.72.034307; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
CHAOS THEORY
CRANKING MODEL
ERBIUM 163
EXCITATION
GAMMA DECAY
GAMMA SPECTRA
KEV RANGE
MEV RANGE
ROTATIONAL STATES
SELECTION RULES
SHELL MODELS
SPIN
STATISTICAL MODELS
YRAST STATES